feat(api): cn-app skeleton, toolchain, env loading convention

Co-Authored-By: Claude Code <noreply@anthropic.com>

packages/contracts/package.json

@@ -4,7 +4,7 @@
   "private": true,
   "type": "module",
   "description": "API contract single source of truth (OpenAPI 3.1 + error codes); types generated via openapi-typescript and committed under src/generated/",
-  "//": "lint script is a placeholder (exit 0): eslint flat config arrives in Task 7. test is a minimal ts-jest scaffold: real type tests arrive in Task 6.",
+  "//": "lint runs `eslint .` against the root flat config (Task 7). test is ts-jest with full type-checking (Task 6 type tests).",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
   "exports": {
@@ -21,7 +21,7 @@
     "build": "tsc -p tsconfig.json && node -e \"require('fs').cpSync('src/generated', 'dist/generated', { recursive: true })\"",
     "typecheck": "tsc --noEmit",
     "test": "jest",
-    "lint": "exit 0"
+    "lint": "eslint ."
   },
   "devDependencies": {
     "@redocly/cli": "^1.0.0",